Actually, reverting to my thread of a couple of days ago about how I heard it in childhood -- Remembering back, it was not so much a hum as a sort of faint hiss, as it might have been the sound of a very distant wind blowing, or somebody sighing non-stop in the next room but one. And in fact I still hear that occasionally — like just now, which brought me back to this thread to emend my previous comment.

Anyone else conscious of what I am talking of here?

≈M≈